1. Field of the Invention
This invention relates to lighting units employing LED (light emitting diode) packages and, more particularly, to beacon lights having LED packages extending radially outward from a cylindrical surface, and to display lights using individual LED packages to display a coherent image.
2. Background Information
Stationary lighting units are used for a number of important purposes, many of which require the placement of a light at a remote location where electrical service is non-existent and where the replacement of batteries used to operate the light is, at best, difficult and expensive. Examples of such applications are beacon lights placed along waterways to indicate buoy locations, navigational hazards, such as rock formations, and dock facilities. In such applications, the visible color and timing (i.e. whether the light is flashing and the sequence of flashes) is determined by the specific use of the light, with specific requirements for lights placed along navigable waterways being determined by government agencies, such as the U.S. Coast Guard. Such lights are generally incandescent types, which are powered, for example, by re-chargeable batteries operating the lights at night and being recharged using solar cells during the day.
Another common use of stationary lighting units is exemplified by flashing yellow warning lights placed along roadways to indicate construction areas and other locations causing traffic to be rerouted or, at least, to be warned away from a hazard, such as road edge next to a steep drop-off. A light of this type is generally configured as an integral unit, including a battery and electronics to provide the flasher function, along with a reflector and fresnel lens forming a housing around an incandescent lamp. Such an integral is typically clamped to a movable barricade, which is placed with other barricades around or along the hazard from which motorists are to be warned.
Two particular disadvantages of using incandescent lamps in applications of this type are the electrical current required and the frequent need for replacing lamps which burn out. The electrical current requirements of the lamp determine that a relatively large battery is required for the application, and that, if the battery is to be recharged during use, as in the marine navigational examples, the photovoltaic cells used to produce current for recharging must be relatively large. What is needed is a lighting system including a sufficiently-visible array of LEDs (Light Emitting Diodes), which typically use much less electrical energy than incandescent lamps. Furthermore, LEDs, since they are far more efficient than incandescent lamps, produce much less heat, allowing their use within and adjacent to plastic optical elements. In typical applications, LEDs last several times as long as incandescent lamps.
While most commercially-available LEDs are built using a single light-emitting chip integrated into a package with a single plastic lens through which light from the chip is refracted, cluster LEDs have been built with a number of segments extending outward from a cylindrical surface. Each such segment includes a light-emitting chip and a plastic lens structure.